What is the hierarchy of available data?
This diagram illustrates the relative confidence in each dataset collected to further understand the aquatic environment (1 - being the most confident). The rationale behind this ordering is:
Wessex Water collects multiple datasets to allow it to perform its essential public health and environmental services. The datasets shown here are collected to understand Wessex Water's impact on the aquatic environment and to help plan investment.
This data source is not yet available in RiverHub, but will be soon.
Wessex Water installs water quality sensors in streams and rivers to provide water quality in real-time data. This data is used to show the levels of ammoniacal nitrogen, conductivity, dissolved oxygen, pH and turbidity and can identify impact from Wessex Water's assets. Over the next ten years, Wessex Water will be installing water quality sensors up and downstream of all clusters of assets like water recycling centers and storm overflows. Sensors can also be used to train artificial intelligence (AI) systems and provide real-time information on parameters that cannot be measured in real-time. At Warleigh Weir, near Bath, Wessex Water have developed a web app that provides real-time information to visitors at Warleigh Weir so that they can make informed decisions in relation to their risks from entering the water (Warleigh Weir App). This uses AI trained by monitoring data and sensors in the river to indicate where water quality may be poor. Please note that sensor data shown here are raw values and therefore may be subject to change when errors are detected.
This data source is not yet available in RiverHub, but will be soon.
This data shows the river quality from sampling locations in the Bristol Avon river catchment. This data is formed of the samples taken from rivers. They are taken by Wessex Water staff (specially trained samplers), returned to our laboratories where the tests are completed, then entered onto our scientific systems. These samples are taken as part of Wessex Water's Water Industry National Environment Programme (WINEP) investigations and are used to understand Wessex Water's impact on the aquatic environment and to help plan future investment to protect public health and environmental quality.
Below are the descriptions of the field name for data in the water quality monitoring dataset:
| Field | Description |
|---|---|
| SampleSiteId | The unique ID for the monitoring location |
| SiteName | Name for the monitoring location |
| DateTime | The time and date the sample was taken |
| Determinand | Name of determinand analysed |
| Qualifier | Denotes whether a result is >/< the limit of detection for the analysis |
| Result | The analytical value |
| Batch | The type of monitoring. See batch code tab |
| modresult | When a sample has a > qualifier 0.5 times the limit of detection (LOD) is used to estimate the determinands concentration |
| DetermWesLabNo | The Wessex Water determinand code |
| Units | Units of determinand analysed |
| Flag | Denotes whether TPO, SRP, NO3 or NH4 concentrations exceeds the 95th percentile concentration expected for the sample location |
| X | The BNGR x coordinate (m) |
| Y | The BNGR y coordinate (m) |
Below are the descriptions of the different batch codes which provide information on the sampling methodology used when taking a sample:
| Batch | Description |
|---|---|
| S0 S | Spot sample taken for capital investigation |
| S0 M | Operator self monitoring sample used for compliance |
| S0 R | Samples taken by operators (these are not MCERTS accredited) |
| S0 A | Deprecated batch code, formally spot samples taken for compliance |
| C3 S | 24-hour composite sample taken for capital investigation |
| C3 M | 24-hour composite sample taken for Urban Waste Water Treatment Directive compliance |
| C3 R | 24-hour composite sample taken by operators (these are not MCERTS accredited) |
| C1 S | Discrete samples taken at multiple times (1-6 hours) during the same day for capital investigation |
| S0 I | Spot sample taken for chemical investigation programme |
| C2 S | Discrete samples taken at multiple times (6-12 hours) during the same day for capital investigation |
This data source is not yet available in RiverHub, but will be soon.
This data shows the and effluent quality samples leaving the WRCs. This data is from samples taken on site. They are taken by Wessex Water staff (specially trained samplers), returned to our laboratories where the tests are completed, then entered onto our scientific systems. This data is used to assess Wessex Water's compliance with its permits. The data is sent to the Environment Agency, who publish the data in their Water Quality Data Archive.
This dataset contains the geographic data where Wessex Water's WRCs discharge into streams and rivers.
Currently only the locations of the WRCs are shown in RiverHub.
This data shows the numerical permit information for flow to full treatment (FFT), dry weather flow (DWF) and discharge limits placed on pollutants such as ammonia, biochemical oxygen demand and total phosphorus. Descriptions of these permits can be found in the How are WRCs permitted? section.
This data source is not yet available in RiverHub, but will be soon.
Population equivalent (PE) is calculated annually, based on multiplying the number of properties by a district specific occupancy rate. Tourism is also considered. Commercial waste is calculated based on supply flow to commercial properties and an estimate of 60g BOD per capita per day. Tankered waste imports are calculated based on COD strength. As the volume of waste is known, therefore a load can be calculated and converted into a PE (using the assumption of 120g COD per capita per day). These can be used to show the relative difference in size between WRCs.
In an effort to increase and improve water quality monitoring, at a time when Environment Agency monitoring is being reduced, the Bristol Avon Rivers Trust (BART) are leading a citizen science 'River Detectives' project kindly funded by Wessex Water.
River Detectives has an important role to play in filling the gaps in water quality monitoring and reconnects people with their local watercourse by empowering local communities with a sense of ownership.
River Detectives supplements BART's annual RiverBlitz citizen science project, providing more frequent and in-depth data for our catchment. Volunteers have been fully trained and provided with their own easy-to-use testing kits, which analyse phosphate, nitrate, temperature and total dissolved solids.
Riverflies are invertebrates that spend most of their life cycle in a river, stream, pond or lake. The three key groups are stoneflies, caddisflies and mayflies. Along with other freshwater invertebrates, they are at the heart of the freshwater ecosystem and are a vital link in the aquatic food chain. Their common characteristics of limited mobility, relatively long life cycle, presence throughout the year, and specific tolerances to changes in environmental conditions make them good indicators of water quality.
The Riverfly Monitoring Initiative (RMI, also known as the Anglers' Riverfly Monitoring Initiative, ARMI) has been pioneered by the Riverfly Partnership to provide a simple, standardised monitoring technique which groups can use to detect any severe perturbations in river water quality, and put them in direct communication with their local ecological contact at the Environment Agency (EA).
Used alongside routine monitoring by the EA, this RMI scheme ensures that water quality is checked more widely, and remedial action is taken at the earliest opportunity if any severe perturbations are detected. This active monitoring also acts as a deterrent to incidental polluters. Successful schemes are underway in catchments across the UK, including across the Bristol Avon catchment.
BART Beacons are volunteers who look for issues and let BART know if they spot opportunities for improvement on their local river. The BART Beacons are individuals or groups who can be a local contact for the public seeking guidance on how to best respond to a problem with their local river.
Over the years the BART Beacons have helped build cases for river restoration, brought communities together to look after their natural spaces and responded quickly to major issues such as pollutions or habitat clearance.
BART can guide the Beacons on the best action to take if they spot an issue or are contacted by a concerned member of the public. This could involve gathering photos to share with BART or reporting an incident to the Environment Agency or local authority.
The RiverHub platform hosts a variety of data sources linked to water quality. Below is some information on the different factors affecting water quality in rivers.
A focus for RiverHub is the levels of phosphorus and nitrogen in our streams and rivers. It is important to be aware that there are a multitude of phosphorus and nitrogen compounds with varying levels of toxicity. Along with other factors, the table below presents common nitrogen and phosphorus compounds that are typically measured in streams and rivers. The Water Framework Directive (WFD) sets targets of water quality parameters for rivers, lakes, groundwater and transitional waterbodies. Although both phosphorus and nitrogen are important nutrients for assessing the impact on rivers, in the UK under the WFD, only nitrogen is included in the assessment of lakes, groundwater and transitional waterbodies health.
Phosphorus is a fundamental nutrient required by all life. It is needed for growth, maintenance, and repair of all living organisms. It is key for the production of the genetic building blocks, DNA and RNA.
Non-toxic in environmentally relevant concentrations.
Consistently high levels of phosphate can lead to eutrophication causing algal growth. Algal bloom can prevent sunlight reaching other vegetation causing changes to ecology.
Excessive algae can affect oxygen levels as bacteria breaks down dead algae.
The Environment Agency classifies phosphate levels in rivers and streams as bad, poor, moderate, good and high. Good status supports a diverse ecology. These classifications are set based on the altitude and the acid buffering capacity (alkalinity) of the streams or rivers and are site specific. In the Bristol Avon the upper class boundaries for good phosphate status range from 0.6 to 0.12 mg/L (ppm). This means that phosphate concentrations need to be on average equal or lower than these values to be good status. On RiverHub we use a simplified system that relates to levels of phosphate measured, not ecological impact, as used by the Environment Agency:
The Environment Agency does not assess total phosphorus (only phosphate levels) when classifying the ecology of a river. However, the targets used for phosphate can be used to indicate if a river or stream is impacted by elevated concentrations of total phosphorus.
| Measured by River Detectives: | ✓ |
| Monitored by Wessex Water: | ✓ |
| Currently available in RiverHub: | ✓ |
Often shortened to just phosphate, it measures the amount in an unfiltered sample. Phosphate is considered the most bioavailable form of phosphorus and easily assimilated by plants and algae and is a good indicator of river health.
| Measured by River Detectives: | ✗ |
| Monitored by Wessex Water: | ✓ |
| Currently available in RiverHub: | ✗ |
Effectively the same as orthophosphate, except small particulate and adsorbed phosphate is eliminated by passing a sample through a 0.45 µm filter. Phosphate is considered the most bioavailable form of phosphorus and easily assimilated by plants and algae and is a good indicator of river health.
| Measured by River Detectives: | ✗ |
| Monitored by Wessex Water: | ✓ |
| Currently available in RiverHub: | ✗ |
Not all phosphorus is in the phosphate form. This measures the total amount of all molecules containing phosphorus. This is important as total phosphorus may breakdown into phosphate. Measuring total phosphate gives us a complete picture of the amount of phosphorus in the environment.
Nitrogen is a fundamental nutrient required by all life. It is needed for growth, maintenance, and repair of all living organisms. It is key for the production of proteins.
| Measured by River Detectives: | ✗ |
| Monitored by Wessex Water: | ✓ |
| Currently available in RiverHub: | ✗ |
Ammonia is extremely toxic but is typically present at very low non-toxic concentrations. Ammonia is the unionised (NH₃). Levels depends on the temperature, pH and ammonium concentrations.
Highly toxic to fish at low concentrations.
There are no targets for ammonia set by the Environment Agency in streams and rivers. Instead, ammoniacal nitrogen is used to access river water quality.
| Measured by River Detectives: | ✗ |
| Monitored by Wessex Water: | ✓ |
| Currently available in RiverHub: | ✗ |
Ammonium is also toxic but less so than ammonia and is typically present at very low non-toxic concentrations. Ammonium is the ionised form of ammonia (NH₄⁺). Ammonium is found in higher concentrations compared with ammonia.
Highly toxic to fish at low concentrations.
There are no targets for ammonium set by the Environment Agency in streams and rivers. Instead, ammoniacal nitrogen used to access river water quality.
| Measured by River Detectives: | ✗ |
| Monitored by Wessex Water: | ✓ |
| Currently available in RiverHub: | ✗ |
Ammoniacal nitrogen is the concentration of both ammonia and ammonium.
Highly toxic to fish at low concentrations.
The Environment Agency classifies ammoniacal nitrogen levels in rivers and streams as bad, poor, moderate, good and high. Good status supports a diverse ecology. These classifications are set based on the altitude and the acid buffering capacity (alkalinity) of the streams or rivers and are site specific. In the Bristol Avon ammoniacal nitrogen upper class boundaries for good status range from 0.3 to 0.6 mg/L (ppm) as a 90th percentile value depending on location. This means that ammoniacal nitrogen concentrations need to be equal or lower than these values 90% of the time to achieve Good status. Percentiles are used for ammoniacal nitrogen to ensure that concentration stay low most of the time.
| Measured by River Detectives: | ✗ |
| Monitored by Wessex Water: | ✓ |
| Currently available in RiverHub: | ✗ |
Nitrite is an intermediate product of the oxidation of ammonia to nitrate. It is highly toxic, but typically present at very low non-toxic concentrations.
Highly toxic to fish at low concentrations.
There are no targets for nitrite set by the Environment Agency in streams and rivers. It is extremely rare that nitrite levels become toxic as it is rapidly oxidised to nitrate.
| Measured by River Detectives: | ✓ |
| Monitored by Wessex Water: | ✓ |
| Currently available in RiverHub: | ✓ |
Nitrate is considered the most bioavailable form of nitrogen and easily assimilated by plants and algae and is a good indicator of river health.
Non-toxic in environmentally relevant concentrations.
Consistently high levels of nitrate can lead to eutrophication causing algal growth. Algal bloom can prevent sunlight reaching other vegetation causing changes to ecology. Excessive algae can affect oxygen levels as bacteria breaks down dead algae.
There are no targets for nitrate set by the Environment Agency in streams and rivers. On RiverHub we use a simplified system that relates to levels of nitrate measured, not ecological impact.
| Measured by River Detectives: | ✗ | |
| Monitored by Wessex Water: | ✓ | (Not routinely) |
| Currently available in RiverHubs: | ✗ |
Urine and amino acids are classed as organic nitrogen compounds. These can breakdown into ammonia in the environment. This process occurs in the sewerage system and at water recycling centres.
Toxic to fish at low concentrations when bacteria metabolise organic nitrogen to ammonia and reduces oxygen availability to the ecology.
There are no targets for organic nitrogen set by the Environment Agency in streams and rivers. Instead the toxic impact of organic nitrogen is assessed using ammoniacal nitrogen.
| Measured by River Detectives: | ✗ | |
| Monitored by Wessex Water: | ✓ | (Not routinely) |
| Currently available in RiverHub: | ✗ |
Urine and amino acids are classed as organic nitrogen compounds. These can breakdown into ammonia in the environment. This process occurs in the sewerage system and at water recycling centres.
Toxicity depends on the proportion of nitrate in relation to the other nitrogen compounds.
There are no targets for total nitrogen set by the Environment Agency in streams and rivers. Instead, the impact of total nitrogen is assessed using ammoniacal nitrogen.
| Measured by River Detectives: | ✗ | |
| Monitored by Wessex Water: | ✓ | |
| Currently available in RiverHub: | ✗ |
BOD is the amount of dissolved oxygen used by micro-organisms in the biological process of metabolising organic matter in water. The more organic matter there is, the greater the BOD. The greater the BOD, the lower the amount of dissolved oxygen is available for animals such as fish. The BOD is therefore an index of the degree of organic pollution in waterbodies. By measuring a sample of water at the start and after five days, we can understand how much oxygen has been used by bacteria. This indicates the biochemical oxygen demand of a water sample.
High BOD can strip the oxygen from water causing fish kills and the death of other aquatic organisms.
The Environment Agency classifies BOD levels in rivers and streams as bad, poor, moderate, good and high. Good status supports a diverse ecology. These classifications are set based on the altitude and the acid buffering capacity (alkalinity) of the streams or rivers and are site specific. In the Bristol Avon BOD upper class boundaries for good status range from 4 to 5 mg/L (ppm) as a 90th percentile value depending on location. This means that BOD concentrations need to be equal or lower than these values 90% of the time to be good status. Percentiles are used for BOD to ensure that concentration stays low most of the time.
| Measured by River Detectives: | ✗ | |
| Monitored by Wessex Water: | ✓ | |
| Currently available in RiverHub: | ✗ |
Chemical oxygen demand (COD): another method of estimating how much oxygen would be depleted from a receiving waterbody as a result of bacterial action. The COD test uses a strong chemical oxidising agent to chemically oxidise the organic material in the wastewater sample under heat and strong acid conditions.
High COD can strip the oxygen from water causing fish kills and the death of other aquatic organisms.
There are no targets for chemical oxygen demand set by the Environment Agency in streams and rivers. Instead, the impact of oxygen demand is assessed using BOD.
| Measured by River Detectives: | ✗ | |
| Monitored by Wessex Water: | ✓ | |
| Currently available in RiverHub: | ✗ |
Suspended solids refer to tiny particles of solid material that are suspended in water. These can include silt, decaying plant and animal matter, industrial wastes, and sewage.
High levels reduce light penetration, impair photosynthesis, clog fish gills, and hinder egg and larval development.
There are no targets for suspended solids set by the Environment Agency in streams and rivers. Instead, the Environment Agency uses other parameters to assess the health of stream and rivers.
| Measured by River Detectives: | ✗ | |
| Monitored by Wessex Water: | ✓ | |
| Currently available in RiverHub: | ✗ |
Conductivity is a measure of water's ability to conduct an electric current, which is directly related to the concentration of ions in the water. It is commonly used to estimate the amount of dissolved salts or inorganic chemicals in the water.
High conductivity can signal pollution and can disrupt aquatic organisms' ionic balance, affecting osmoregulation.
There are no targets for conductivity set by the Environment Agency in streams and rivers. This is a useful indicator parameter that is used to help indicate the reasons for elevated concentrations of other chemicals.
| Measured by River Detectives: | ✓ |
| Monitored by Wessex Water: | ✓ |
| Currently available in RiverHub: | ✓ |
Temperature is a measure of the warmth or coldness of the water. It is a critical parameter that affects many chemical and biological processes in aquatic ecosystems.
Rapid temperature changes cause thermal shock and reduce dissolved oxygen, impacting breeding and stressing aquatic life.
A consistent change in temperature can cause shifts in the ecological functioning of a river. Climate change is a significant concern for our streams and rivers.
The Environment Agency classifies temperature in rivers and streams as bad, poor, moderate, good and high. Good status supports a diverse ecology. These classifications are set based on whether the stream or river support salmonid (Salmon and Trout) or cyprinid (carp and roach) fish. In the Bristol Avon temperature upper class boundaries for good status are 23 or 28 degree Celsius for salmonid and cyprinid type rivers and streams respectively as a 98th percentile value. This means that temperature needs to be equal or lower than these values 98% of the time to be good status.
| Measured by River Detectives: | ✓ |
| Monitored by Wessex Water: | ✓ |
| Currently available in RiverHub: | ✓ |
Dissolved solids refer to any minerals, salts, metals, cations, or anions dissolved in water. They are often measured as total dissolved solids (TDS).
High levels affect water clarity and salinity, disrupting aquatic organisms' osmotic balance.
There are no targets for dissolved solids set by the Environment Agency in streams and rivers. This is useful indicator parameter that is used to help explain elevated concentrations of other chemicals.
| Measured by River Detectives: | ✗ |
| Monitored by Wessex Water: | ✓ |
| Currently available in RiverHub: | ✓ |
Dissolved oxygen (DO) is the amount of oxygen that is present in water. It is essential for the respiration of aquatic organisms and the decomposition of organic matter.
Low DO levels cause hypoxia, stressing or killing fish and other aquatic organisms.
The Environment Agency classifies dissolved oxygen in rivers and streams as bad, poor, moderate, good and high. Good status supports a diverse ecology. These classifications are set based on whether the stream or river supports salmonid (Salmon and Trout) or cyprinid (carp and roach) fish, the elevation and the acid buffering capacity (alkalinity). These are site specific. In the Bristol Avon dissolved oxygen upper class boundaries for good status is either 75% or 60% saturation as a 10th percentile value. This means that dissolved oxygen saturation cannot be lower than these values 10% of the time to be good status.
| Measured by River Detectives: | ✗ |
| Monitored by Wessex Water: | ✓ |
| Currently available in RiverHub: | ✗ |
E. coli (Escherichia coli) is a type of bacteria commonly found in the intestines of warm-blooded organisms. Its presence in water is an indicator of faecal contamination.
High E. coli levels pose health risks, causing gastrointestinal illness. High levels also suggest the potential presence of other pathogens.
The Environment Agency classifies coastal and inland bathing waters as 'excellent', 'good', 'sufficient' or 'poor' quality. To achieve good status, E. coli concentrations need to be lower than 1,000 colony forming units (cfu) per 100 mL of sample 95% of the time.
| Measured by River Detectives: | ✗ |
| Monitored by Wessex Water: | ✓ |
| Currently available in RiverHub: | ✗ |
Intestinal Enterococci are a group of bacteria found in the intestines of humans and animals. They are used as indicators of faecal contamination in water.
High levels suggest health risks and potential presence of other pathogens.
The Environment Agency classifies coastal and inland bathing waters classified as 'excellent', 'good', 'sufficient' or 'poor' quality. To achieve good status, Intestinal Enterococci concentrations need to be lower than 400 colony forming units (cfu) per 100 mL of sample 95% of the time.
| Measured by River Detectives: | ✗ |
| Monitored by Wessex Water: | ✓ |
| Currently available in RiverHub: | ✗ |
Iron is a naturally occurring element that can be present in water as a result of geological formations or industrial processes. It is often found in the form of dissolved ferrous iron (Fe₂⁺) or ferric iron (Fe₃⁺).
High concentrations stain surfaces, taste unpleasant, clog pipes, and harm aquatic life by precipitating on gills.
The Environment Agency sets a long-term target of 1 mg/L.
| Measured by River Detectives: | ✗ |
| Monitored by Wessex Water: | ✓ |
| Currently available in RiverHub: | ✗ |
pH is a measure of how acidic or basic the water is, on a scale of 0 to 14, with 7 being neutral. It is influenced by various factors including geological formations, industrial discharges, and biological processes.
Extreme pH levels harm aquatic life, increase metal toxicity (low pH), and reduce nutrient availability (high pH).
The Environment Agency classifies pH in rivers and streams as poor, moderate, good and high. Good status supports a diverse ecology. To achieve good pH a stream or river needs to be between 6 and 9, 90% of the time.
For more information about these parameters and challenges facing the water environment, the Environment Agency has compiled a set of useful documents here:
River basin planning: challenges for the water environment